For questions about the non-competing label. Non-competing is a retired label used on answers that are "non-competing" i.e. they are valid answers but ineligible to win. The "non-competing" label has now been fully retired, and should not added to new answers
Answers would be marked "non-competing" to indicate that they were valid answers, but ineligible to win. The most common usage of the term was for answers written in languages that post-date the challenge. However, since newer languages are allowed by default now, this no longer applies and the non-competing label has been fully retired.
Note that, even if marked as non-competing, invalid answers are not allowed and should be removed per site rules.